In ICS, there was an on/off toggle in Settings-->Data usage...but I'm not seeing that in JB. How can I toggle mobile data now (without needing some 3rd party widget)?
Not sure this is what you are asking about or not, but if you want to turn Data usage on/off, go to Settings > then under Wireless and Networks, select More... > Mobile Networks > Data enabled. You can also turn OFF 4g LTE on that same screen by selecting Network Mode and choosing CDMA.